Which is the heaviest man-made element discovered so far?

The heaviest man-made element discovered so far is Oganesson (Og), which was formerly known by its temporary name Ununoctium (Uuo). It has the atomic number 118 and sits at the bottom of the noble gas group in the periodic table. Oganesson was officially recognized by the International Union of Pure and Applied Chemistry (IUPAC) in 2016. It is named after the Russian scientist Yuri Oganessian, who played a major role in its discovery.

Oganesson is a synthetic element, meaning it does not occur naturally on Earth. It was produced in a laboratory by bombarding californium-249 with calcium-48 ions in a particle accelerator. This high-energy collision briefly created atoms of Oganesson, which existed for less than a millisecond before decaying into lighter elements. Because of this extremely short half-life, scientists cannot study it directly under normal laboratory conditions.

With an atomic weight around 294, Oganesson is currently the heaviest element known to science. It belongs to the noble gas group (Group 18) of the periodic table, but unlike lighter noble gases such as helium or neon, it is predicted to behave quite differently. Due to strong relativistic effects, its electrons move at very high speeds, giving it unique chemical properties. Some studies suggest that Oganesson might not be a gas at room temperature but rather a solid or semiconducting material — a surprising trait for a noble gas.

The discovery of Oganesson is a major achievement in nuclear and atomic chemistry, as it pushes the boundaries of the periodic table to the so-called “island of stability.” Scientists continue to study superheavy elements like Oganesson to understand the forces that hold atomic nuclei together and to explore how new elements can be synthesized.

In summary, Oganesson (Og) — previously called Ununoctium (Uuo) — is the heaviest man-made element discovered to date, representing the frontier of modern chemistry and nuclear research.